Optimum Production and Characterization of an Acid Protease from Marine Yeast Metschnikowia reukaufii W6b

The marine yeast strain W6b isolated from sediment of the South China Sea was found to produce a cell-bound acid protease.The crude acid protease produced by this marine yeast showed the highest activity at pH 3.5 and 40 ℃.The optimal pH and temperature for the crude acid protease were in agreement with those for acid protease produced by the terrestrial yeasts.The optimal medium of the acid protease production was seawater containing 1.0% glucose, 1.5% casein, and 0.5% yeast extract, and the optimal cultivation conditions of the acid protease production were pH 4.0, a temperature of 25 ℃ and a shaking speed of 140 rmin-1.Under the optimal conditions, 72.5 UmL-1 of acid protease activity could be obtained in cell suspension within 48 h of fermentation at shake flask level.The acid protease production was induced by high-molecular-weight nitrogen sources and repressed by low-molecu-lar-weight nitrogen sources.Skimmed-milk-clotting test showed that the crude acid protease from the cell suspension of the yeast W6b had high skimmed milk coagulability.The acid protease produced by M.reukaufii W6b may have highly potential applications in cheese, food and fermentation industries.

Application of acid protease in the industrial production of corn ethanol

Bioethanol is a renewable,clean energy and a very important basic chemical raw material,improving production efciency and reducing production cost are the goals pursued by ethanol enterprises.Adding acid protease in the process of producing ethanol from grain will have many efects on fermentation,one of the most concerned efects is to increase liquor yield.Acid protease can hydrolyze the protein in cereals to produce free amino acids that can be used directly by yeast,thus reducing the amount of sugar consumed for amino acid metabolism,and allowing more sugar to be converted to ethanol.The application method and efect of acid protease in the industrial production of ethanol from corn were studied in this study,the results showed that the addition of acid protease at the dosage of 10 U/g(raw material)during yeast seeding could replace urea,promote yeast proliferation,reduce the infection rate,shorten the fermentation period by 7.5 h and increase the alcohol yield of raw materials by 0.33 percentage point.When acid protease was used in ethanol production line with an annual output of 180,000 tons,the net proft increased by at least US$4900/day compared with the control process.It is hoped that this study can lay a foundation for the application of acid protease in ethanol industry.

Arabidopsis small ubiquitin-related modifier protease ASP1 positively regulates abscisic acid signaling during early seedling development~~

The small ubiquitin-related modifier （SUMO） modification plays an important role in the regulation of abscisic acid （ABA） signaling, but the function of the SUMO protease, in ABA signaling, remains largely unknown. Here, we show that the SUMO protease, ASPI positively regulates ABA signaling. Mutations in ASPI resulted in an ABA-insensitive phenotype, during early seedling develop- ment. Wild-type ASP1 successfully rescued, whereas an ASPI mutant （C577S）, defective in SUMO protease activity, failed to rescue, the ABA-insensitive phenotype of asp1-1. Expression of ABI5 and MYB3o target genes was attenuated in asp^-I and our genetic analyses revealed that ASP1 may function upstream of ABI5 and MYB3o.

Application of acidic protease in the pickling to simplify the pelt bating process

Traditionally,universally used pelt bating technologies rely on the application of trypsin,neutral and alkaline microbial proteases but suffer from complicated operation,limited bating efficiency and unsatisfac-tory leather performance.Therefore,devising a new pelt bating approach to achieve high bating efficiency and excellent leather performance has always been wished for by the leather industry.To pursue this goal,years of persistent research work enabled us to develop a novel approach for pelt bating by means of acidic proteases in pickling process.Initially,basic enzymatic characteristics and bating effectiveness of several typical acidic pro-teases in pelt pickling medium were investigated;then,the bating effectiveness through the quantitative charac-terization of protease activity of the optimal acidic protease was compared with that of the conventional bating enzyme.The results indicated that all of the selected acidic proteases had good salt-tolerance and exhibited optimum activity at pH 3.0–4.0.The novel pickling-bating method based on microbial origin acidic protease L80A led to an outstanding performance on pelt bating at the dosage of 150 U/mL of collagenolytic activity.The bating effectiveness of acidic protease L80A was comparable to and even better than that of trypsin BEM due to its mod-erate proteolytic ability.Moreover,the deep and even penetration of acidic protease in the pelt permitted it to produce soft,organoleptically stable and overall better quality crust leather than that of the conventional trypsin bating method.Additionally,pelt bating was performed along with the pickling process without extra inactiva-tion and washing operation,making the bating operation more efficient,economical,and environment friendly.Results had made us to conclude that this cutting-edge acidic proteases based pickling-bating method could be the first step/way forward to replace the decades-old traditional pelt bating technology.

Antioxidant Activity of Peptides Obtained from Cotton Ground Oil-Cake Proteins

Antioxidant activity of the peptides derived from proteins of defatted cottonseed kernels and cotton ground oil-cake by their enzymatic hydrolysis with acidic （Asp. niger） and neutral proteinases （Bac. amyloliquefaciens） was studied. Antioxidant activity of the derived peptides depended on the used proteins and enzymes. The peptides derived by using of neutral proteinase possessed higher antioxidant activity, in comparison with the peptides derived by acidic proteinases.